An Alternative View of Quantum Mechanics

Anastass Anastasov

David Ferry

All alternative interpretations have at their roots some form of disgust at the Copenhagen–Gottingen philosophy, and all have a desire to seek an alternative truth for the understanding of quantum mechanics. The alternative view is of an intrinsic reality prior to the measurement, as discussed by A. Einstein, and by most of the founders of the wave theory of quantum mechanics. A key point of Neils Bohr’s arguments with Einstein, particularly with regard to the Einstein–B. Podolsky–N. Rosen type of experiments, was that one could not make multiple measurements on the same particle, or quantum system. In his view, the measurement itself defined the quantum system. With the arrival of the Schrodinger equation, quantum mechanics had a causal, deterministic equation of motion for the wave function. Perturbation theory, based upon the Schrodinger equation, provided transition details that undermined the assertions of quantum jumps.

Yakir Aharonov

Dennis Dieks

According to classical physics, particles are basic constituents of the physical world. Quantum theory is much less friendly to particles; in particular, relativistic quantum field theory (RQFT) creates serious obstacles for the idea that particles are fundamental. Apparently, when moving from the domain of RQFT to that of classical mechanics (CM), particles have to emerge at some stage. It is standard to assume that this emergence has been completed at the level of quantum mechanics, halfway between RQFT and CM, even though particles of the same kind in many-particle quantum mechanics have the curious feature of being ‘entities without identity’. Against this ‘Received View’ about the nature of quantum particles we outline and defend an Alternative View (AV), in which the emergent character of particles is emphasized. According to this AV, the step to a particle theory has not yet been made in quantum mechanics: conditions have still to be satisfied in order to make the particle concept applicable. If these conditions are met, the quantum particles that emerge are distinguishable individuals possessing physically defined identities, in stark contrast to what the Received View asserts. We will compare and contrast the two Views, both from a physical and a logical/conceptual point of view. This article is part of the theme issue ‘Identity, individuality and indistinguishability in physics and mathematics’.

Arkady Plotnitsky, Luigi Accardi, Guillaume Adenier +5 more

This paper critically examines the view of quantum mechanics that emerged shortly after the introduction of quantum mechanics and that has been widespread ever since. Although N. Bohr, P. A. M. Dirac, and W. Heisenberg advanced this view earlier, it is best exemplified by J. von Neumann’s argument in Mathematical Foundations of Quantum Mechanics (1932) that the transformation of “a [quantum] state … under the action of an energy operator … is purely causal,” while, “on the other hand, the state … which may measure a [given] quantity … undergoes in a measurement a non‐casual change.” Accordingly, while the paper discusses all four of these arguments, it will especially focus on that of von Neumann. The paper also offers an alternative, noncausal, view of the quantum‐mechanical situation and considers the differences between the ensemble and the Bayesian approaches to quantum mechanics from this perspective.

Jochen Pade